Listing we opened and checked. Match the diameter, length and both fittings on this page before you order. The price is on Amazon; we do not print one.
Nordic Hot Tubs OEM CARTRIDGE-T35 spa filter (4CH-935)
Nordic Hot Tubs
Replacement numbers
Unicel 4CH-935, Pleatco PWW35L
Fits Nordic Hot Tubs OEM CARTRIDGE-T35, 31CARTRIDGE-T35.
Diameter 4-15/16" (125 mm)Length 9-1/4" (235 mm)35 sq ft7 models listedUnicel 4CH-935
Disclosure: we may earn a commission from qualifying purchases made through retailer links on this site, at no extra cost to you. As an Amazon Associate I earn from qualifying purchases. Check price on Amazon opens the Unicel 4CH-935 listing we checked. These are affiliate links. Product photos are omitted unless Amazon supplied one through the Product Advertising API or a SiteStripe image link. Verify dimensions before ordering. Each “Check price on Amazon” button opens a specific listing whose title we checked. The line under the name repeats only that title. See our affiliate disclosure.
| Unicel | 4CH-935 |
|---|---|
| Pleatco | PWW35L |
| Filbur | not found in Filbur catalog |
| Top | v-groove semi-circular handle |
| Bottom | 2" female SAE thread |
Bottom: 2" female SAE thread
Drawn to scale from the listed diameter and length. Handles, threads and closed ends are drawn as symbols, not to scale. 35 sq ft media.
Nordic Hot Tubs files this cartridge as 4CH-935 cartridge, in the Nordic Hot Tubs group. Numbers on the row: OEM CARTRIDGE-T35, 31CARTRIDGE-T35; Unicel 4CH-935; Pleatco PWW35L. 4-15/16" across, 9-1/4" long, top v-groove semi-circular handle, bottom 2" female SAE thread, 35 sq ft.
What the sources add about CARTRIDGE-T35: Nordic Hot Tubs' own 2023 filter chart lists CARTRIDGE-T35 as Unicel 4CH-935, Pleatco PWW35L and Waterway 817-4035, with no Filbur number. Nordic's owner's manual gives the same size: 9-1/4" long, 4-15/16" across, handle top, 2" SAE female thread, 35 sq ft. Nordic's 2022 parts list sells it as 31CARTRIDGE-T35 for the Teleweir housing. Unicel's spec table says it fits a 1-1/2" male SAE stand pipe.
Model list attached to 4CH-935 cartridge: Nordic Crown, years after 2014, listed by Nordic Hot Tubs filter chart (2023) (CARTRIDGE-T35, threaded 35 sq ft); Nordic 110 Crown, no year range printed, listed by Nordic Hot Tubs filter chart (2023) (CARTRIDGE-T35, threaded 35 sq ft); Nordic D'Amour: 110 D'Amour, D'Amour MS, D'Amour SE, no year range printed, listed by Nordic Hot Tubs filter chart (2023) (CARTRIDGE-T35, threaded 35 sq ft); Nordic Encore: Encore, Encore Pre, 110 Encore, Encore MS, SE, LS, no year range printed, listed by Nordic Hot Tubs filter chart (2023) (CARTRIDGE-T35, threaded 35 sq ft); Nordic Jubilee: 110 Jubilee, Jubilee MS, SE, LS, no year range printed, listed by Nordic Hot Tubs filter chart (2023) (CARTRIDGE-T35, threaded 35 sq ft); Nordic Retreat: Retreat, 110 Retreat, Retreat MS, SE, no year range printed, listed by Nordic Hot Tubs filter chart (2023) (CARTRIDGE-T35, threaded 35 sq ft); Nordic Stella: Stella, 110 Stella, Stella MS, SE, no year range printed, listed by Nordic Hot Tubs filter chart (2023) (CARTRIDGE-T35, threaded 35 sq ft).
Filbur does not have a number on this row. Search CARTRIDGE-T35 or the Nordic Hot Tubs part you pulled out of the spa.
Left blank on purpose: no Filbur equivalent (Nordic's chart prints NA); Pleatco's spec table prints PWW35L as 5" x 8-1/2" with a 1-1/2" bottom, not 4-15/16" x 9-1/4"; Nordic's chart has no Crown entry for 2008-2014.
Source locations for this Nordic Hot Tubs row: Unicel 2026 Replacement Guide on 4CH-935 (OEM cross reference (Nordic Hot Tubs section), PDF p.46 (printed p.42); spec table PDF p.8 (printed p.4)). Pleatco 2023 Catalog on 4CH-935 (Unicel-to-Pleatco cross reference, PDF p.47 (4CH-935 = PWW35L)). Nordic Hot Tubs filter chart (2023) on 4CH-935 (CARTRIDGE-T35 row: Unicel 4CH-935, Pleatco PWW35L, Filbur NA, Waterway 817-4035; model list). Nordic Hot Tubs owner's manual (01.2024) on 4CH-935 (Filter Quick Reference by Model, p.22: CARTRIDGE-T35, 9-1/4" x 4-15/16", handle top, 2" SAE female thread, 35 sq ft).
Hot tubs listed for this cartridge
The rest of the Nordic Hot Tubs model list is the Nordic Hot Tubs filter by model and year lookup.
| Model / system | Years | Listed by |
|---|---|---|
| Nordic Crown (CARTRIDGE-T35, threaded 35 sq ft) | after 2014 | Nordic Hot Tubs filter chart (2023) |
| Nordic 110 Crown (CARTRIDGE-T35, threaded 35 sq ft) | not given | Nordic Hot Tubs filter chart (2023) |
| Nordic D'Amour: 110 D'Amour, D'Amour MS, D'Amour SE (CARTRIDGE-T35, threaded 35 sq ft) | not given | Nordic Hot Tubs filter chart (2023) |
| Nordic Encore: Encore, Encore Pre, 110 Encore, Encore MS, SE, LS (CARTRIDGE-T35, threaded 35 sq ft) | not given | Nordic Hot Tubs filter chart (2023) |
| Nordic Jubilee: 110 Jubilee, Jubilee MS, SE, LS (CARTRIDGE-T35, threaded 35 sq ft) | not given | Nordic Hot Tubs filter chart (2023) |
| Nordic Retreat: Retreat, 110 Retreat, Retreat MS, SE (CARTRIDGE-T35, threaded 35 sq ft) | not given | Nordic Hot Tubs filter chart (2023) |
| Nordic Stella: Stella, 110 Stella, Stella MS, SE (CARTRIDGE-T35, threaded 35 sq ft) | not given | Nordic Hot Tubs filter chart (2023) |
Check the cartridge you removed
Measure diameter, length, and both ends, then compare them with the figures above. The steps are in the measuring guide. Why the bottom decides whether it seals: open-end vs threaded filters. Power, the retainer, and not running the spa empty: how to install a cartridge. Number formats: how Filbur, Unicel and Pleatco numbers compare.
The same 4CH-935 number is also on the Waterway Plastics page.
Every number on this row, on one screen: cross-reference lookup. Published clean and replace intervals for this cartridge, and a buy link for the numbers above: replacement schedule and reorder. The interval comparison by brand: calculator.
Cleaner and test strips
Hose rinse and soak steps are in how to clean a cartridge. Named cleaners and strips are in filter cleaners and test strips.
Filter cleaner and test strips
-
Leisure Time O Filter Clean Cartridge Cleaner Listing title: cartridge cleaner, 32 fl oz.
-
SpaGuard Filter Cleaner Listing title: filter cleaner for spas and hot tubs, 1 quart.
-
AquaChek SPA 6-in-1 Test Strips Listing title: reads total bromine, total chlorine, free chlorine, pH, total alkalinity and total hardness.
Unicel 4CH-935 Listing we opened and checked. Match the diameter, length and both fittings on this page before you order. The price is on Amazon; we do not print one.
Sources
- Unicel 2026 Replacement Guide: OEM cross reference (Nordic Hot Tubs section), PDF p.46 (printed p.42); spec table PDF p.8 (printed p.4) (PDF)
- Pleatco 2023 Catalog: Unicel-to-Pleatco cross reference, PDF p.47 (4CH-935 = PWW35L) (PDF)
- Nordic Hot Tubs filter chart (2023): CARTRIDGE-T35 row: Unicel 4CH-935, Pleatco PWW35L, Filbur NA, Waterway 817-4035; model list (PDF)
- Nordic Hot Tubs owner's manual (01.2024): Filter Quick Reference by Model, p.22: CARTRIDGE-T35, 9-1/4" x 4-15/16", handle top, 2" SAE female thread, 35 sq ft (PDF)
Not in sources: no Filbur equivalent (Nordic's chart prints NA); Pleatco's spec table prints PWW35L as 5" x 8-1/2" with a 1-1/2" bottom, not 4-15/16" x 9-1/4"; Nordic's chart has no Crown entry for 2008-2014.